RIS

T1 - New nitrogen-containing materials for hydrogen storage and their characterization by high-pressure microbalance

AU - Vestbø,Andreas Peter

A2 - Bjerrum,Niels

A2 - Jensen,Jens Oluf

A2 - Barner,Jens H. Von

PY - 2009/4

Y1 - 2009/4

N2 - Hydrogen storage for practical applications is under intense scrutiny worldwide since hopes are
prevalent of being able to use hydrogen as energy vector in a continually difficult time in terms of
having access to clean and affordable energy in the world. Hydrogen can be stored in compressed or
liquid form, technologies that are well developed and usable, but not energy efficient. Certain
metals and alloys are able to contain hydrogen within practical pressure and temperature ranges
very efficient volume-wise, but they are too heavy for use in cars. Recently, attention has turned to
the so-called complex hydrides, which contain hydrogen bound covalently often in very light
materials involving elements such as lithium, sodium, nitrogen and aluminum. While these
materials typically have high decomposition temperatures, the combination with other compounds
helps to destabilize the material resulting in lowered effective dehydrogenation temperatures.
From the discovery in 1996 by Borislav Bogdanović and his group that catalyzed sodium alanate,
NaAlH4, can release hydrogen reversibly below 200 °C relatively fast, hydrogen storage in
nitrogen-containing compounds beginning with lithium nitride, Li3N, was considered a next major
step in the succession of research in complex hydrides. Many complex hydrides involving nitrogen
are presently under examination. This thesis reviews some of the results so far and embarks on a
study of hydrogen storage in some of the compounds.
Following a brief introduction in Chapter 1, Chapter 2 of the text deals with general principles and
an overview for hydrogen storage in solid materials.
Chapter 3-5 deals with the development of an in-house high pressure microbalance in a glovebox
built from scratch for the use of characterizing new hydrogen storage materials including giving an
example of characterization on a well-known hydrogen storage material, CaNi5.
Chapter 6 contains results on a new system based on Li, Al and N for hydrogen storage. It was
shown that Li3AlN2 can be synthesized from Li3N and Al under nitrogen pressure. Furthermore, the
compound was proven to be able to store hydrogen reversibly.
Chapter 7 describes first time results for a new hydrogen system based on Li, Si, and N. It discusses
the synthesis of Li5SiN3 and Li2SiN2. Li5SiN3 was treated in-depth and was seen to be able to store
hydrogen reversibly at fairly moderate conditions. Furthermore, the effect of doping a system of
lithium amide and silicon, LiNH2+Si, with TiCl3 was examined, showing vastly improved
desorption conditions with increased doping loads.
Chapter 8 is about the newly publicized “hydrogen” pill, which in this work was attempted to be
turned into a real hydrogen pill as opposed to an ammonia pill. The findings point to the possibility
of combining the material in the ammonia pill with other compounds, which make it possible to
store hydrogen reversibly.

AB - Hydrogen storage for practical applications is under intense scrutiny worldwide since hopes are
prevalent of being able to use hydrogen as energy vector in a continually difficult time in terms of
having access to clean and affordable energy in the world. Hydrogen can be stored in compressed or
liquid form, technologies that are well developed and usable, but not energy efficient. Certain
metals and alloys are able to contain hydrogen within practical pressure and temperature ranges
very efficient volume-wise, but they are too heavy for use in cars. Recently, attention has turned to
the so-called complex hydrides, which contain hydrogen bound covalently often in very light
materials involving elements such as lithium, sodium, nitrogen and aluminum. While these
materials typically have high decomposition temperatures, the combination with other compounds
helps to destabilize the material resulting in lowered effective dehydrogenation temperatures.
From the discovery in 1996 by Borislav Bogdanović and his group that catalyzed sodium alanate,
NaAlH4, can release hydrogen reversibly below 200 °C relatively fast, hydrogen storage in
nitrogen-containing compounds beginning with lithium nitride, Li3N, was considered a next major
step in the succession of research in complex hydrides. Many complex hydrides involving nitrogen
are presently under examination. This thesis reviews some of the results so far and embarks on a
study of hydrogen storage in some of the compounds.
Following a brief introduction in Chapter 1, Chapter 2 of the text deals with general principles and
an overview for hydrogen storage in solid materials.
Chapter 3-5 deals with the development of an in-house high pressure microbalance in a glovebox
built from scratch for the use of characterizing new hydrogen storage materials including giving an
example of characterization on a well-known hydrogen storage material, CaNi5.
Chapter 6 contains results on a new system based on Li, Al and N for hydrogen storage. It was
shown that Li3AlN2 can be synthesized from Li3N and Al under nitrogen pressure. Furthermore, the
compound was proven to be able to store hydrogen reversibly.
Chapter 7 describes first time results for a new hydrogen system based on Li, Si, and N. It discusses
the synthesis of Li5SiN3 and Li2SiN2. Li5SiN3 was treated in-depth and was seen to be able to store
hydrogen reversibly at fairly moderate conditions. Furthermore, the effect of doping a system of
lithium amide and silicon, LiNH2+Si, with TiCl3 was examined, showing vastly improved
desorption conditions with increased doping loads.
Chapter 8 is about the newly publicized “hydrogen” pill, which in this work was attempted to be
turned into a real hydrogen pill as opposed to an ammonia pill. The findings point to the possibility
of combining the material in the ammonia pill with other compounds, which make it possible to
store hydrogen reversibly.

KW - Hydrogen storage

M3 - Ph.D. thesis

BT - New nitrogen-containing materials for hydrogen storage and their characterization by high-pressure microbalance